Room: Exhibit Hall | Forum 4
Purpose: To develop an automatic treatment planning strategy for volumetric modulated arc therapy enabled total body irradiation (VMAT-TBI).
Methods: In the treatment planning of linac-based VMAT-TBI, two CT scans are acquired to cover entire body of patients who are taller than 140cm. One is head-first supine (HFS) and the other is feet-first supine (FFS). Instead of merging both image sets manually, an in-house software was developed by using fixed radio opaque markers on a custom designed VMAT-TBI frame to align FFS images onto HFS ones. Two types of treatment plans are created automatically in DICOM format, a dynamic arc plan to cover the upper body till part of thigh, and an AP-PA IMRT plan for the rest of lower extremities. The arc plan is often designed with 6-7 arcs for 4 isocenters while they are 25 cm apart from each other in mid-plane. The IMRT plan has several AP-PA fields with different isocenters depending on the patient height. The most inferior arc isocenter is 25 cm from the most superior AP-PA isocenter. The generated DICOM files are imported to Eclipse server and then the body is contoured automatically by using Eclipse scripting. The script further performs the plan optimization for the arc VMAT and AP-PA IMRT.
Results: A python platform is designed and running in the background. After both CT scans are pushed to the platform, the software aligns and merges CT images, followed by isocenters placement and beam configurations. The final CT and the treatment plans are imported to Eclipse. An experiment was performed by using a full length human phantom. The working in progress using Eclipse C# scripting in version 15.5 is designed for automatic contour segmentation and plan optimization.
Conclusion: We have developed a semi-automatic planning system that will increase the efficiency of our VMAT-TBI planning.
TH- External beam- photons: treatment planning/virtual clinical studies